New Classification for Periprosthetic Distal Femoral Fractures Based on Locked-Plate Fixation Following Total Knee Arthroplasty: A Multicenter Study

BackgroundThis study aimed to establish a new classification using locked-plate fixation for periprosthetic distal femoral fracture (PDFF) following total knee arthroplasty (TKA) and to determine when dual locked-plate fixation is necessary through defining this classification.MethodsOne-hundred fifteen consecutive PDFFs that underwent operative treatment were reviewed from 2011 to 2019 with minimum 1-year follow-up. Most PDFFs were fixed with single or dual locked-plate fixations using the minimally invasive plate osteosynthesis technique. Based on preoperative radiographs, PDFFs were classified according to the level of main fracture line relative to the anterior flange of femoral component: type I and II, main fracture line located proximal and distal to the anterior flange; and type III, component instability regardless of fracture line requiring revisional TKA. Furthermore, type II fractures were subclassified based on the direction of fracture beak as follows: type II_L, lateral-beak; type II_M, medial-beak. The incidence, treatment methods, and complications were analyzed according to the classification.ResultsIncidences of type I, II_L, II_M, and III were 64.4%, 8.7%, 24.3%, and 2.6%, respectively. Meanwhile, most PDFFs in type I and II were treated with lateral single locked-plate fixations, except for type II_M, which was treated with either single or dual locked-plate fixations. Overall complications were significantly higher in type II (28.9%) than in type I (10.8%, P = .019). In type II_M, bone union–related complications were significantly higher in single locked-plate fixation (50.0%) than in dual locked-plate fixation (5.6%; P = .013).ConclusionThe new classification provides practical and obvious strategies for the treatment of PDFF following TKA using locked-plate fixation. For type II_M fracture, dual plate fixation is necessary to prevent fixation failure or nonunion.     

Next-Generation Sequencing vs Culture-Based Methods for Diagnosing Periprosthetic Joint Infection After Total Knee Arthroplasty: A Cost-Effectiveness Analysis

BackgroundPeriprosthetic joint infection (PJI) after total knee arthroplasty is challenging to diagnose. Compared with culture-based techniques, next-generation sequencing (NGS) is more sensitive for identifying organisms but is also less specific and more expensive. To date, there has been no study comparing the cost-effectiveness of these two methods to diagnose PJI after total knee arthroplasty.MethodsA Markov, state-transition model projecting lifetime costs and quality-adjusted life years (QALYs) was constructed to determine the cost-effectiveness from a societal perspective. The primary outcome was incremental cost-effectiveness ratio, with a willingness-to-pay threshold of $100,000/QALY. Sensitivity analyses were performed to evaluate parameter assumptions.ResultsAt our base case values, culture was not determined to be cost-effective compared to NGS, with an incremental cost-effectiveness ratio of $422,784 per QALY. One-way sensitivity analyses found NGS to be the cost-effective choice above a pretest probability of 45.5% for PJI. In addition, NGS was cost-effective if its sensitivity was greater than 70.0% and its specificity greater than 94.1%. Two-way sensitivity analyses revealed that the pretest probability and test performance parameters (sensitivity and specificity) were the largest factors for identifying whether a particular strategy was cost-effective.ConclusionThe results of our model suggest that the cost-effectiveness of NGS to diagnose PJI depends primarily on the pretest probability of PJI and the performance characteristics of the NGS technology. Our results are consistent with the idea that NGS should be reserved for clinical contexts with a high pretest probability of PJI. Further study is required to determine the indications and subgroups for which NGS offers clinical benefit.     

Prevalence of Postoperative Periprosthetic Femur Fractures Between Two Different Femoral Component Designs Used in Direct Anterior Total Hip Arthroplasty

BackgroundPeriprosthetic femur fractures are a well-documented complication following direct anterior uncemented total hip arthroplasty. The purpose of this study is to compare the prevalence of postoperative periprosthetic femur fractures between 2 different femoral component designs used in direct anterior total hip arthroplasty.MethodsBeginning in February 2015, a single fellowship-trained adult reconstruction surgeon performed 361 consecutive direct anterior total hip replacements using a flat, single-taper, wedged femoral implant. In June 2016, that same surgeon, using the exact same surgical technique and postoperative weight-bearing protocol, began using a dual-taper, hydroxyapatite-coated implant for 789 consecutive hips. The patients were carefully monitored for 3 months after surgery to identify the frequency of periprosthetic femur fractures. A Fisher’s exact test was used to determine if the prevalence of periprosthetic femur fractures differed between the 2 implant designs.ResultsFive of 361 (1.4%) patients sustained proximal femur fractures at an average of 19.6 days postoperatively in the first group, all demonstrating a Vancouver type B2 periprosthetic fracture and requiring femoral revision. No patients (0/789, 0%) in the second cohort sustained a postoperative, periprosthetic fracture (P = .006).ConclusionIn this comparison of 2 consecutive cohorts, the dual-taper, hydroxyapatite-coated implant had a statistically significant lower postoperative periprosthetic fracture rate than a flat, single-taper, wedged design.     

Risk Factors for Intraoperative Periprosthetic Femoral Fractures During Primary Total Hip Arthroplasty. An Analysis From the National Joint Registry for England and Wales and the Isle of Man

BackgroundThe aim of this study is to estimate risk factors for intraoperative periprosthetic femoral fractures (IOPFF) and each anatomic subtype (calcar crack, trochanteric fracture, femoral shaft fracture) during primary total hip arthroplasty.MethodsThis retrospective cohort study included 793,823 primary total hip arthroplasties between 2004 and 2016. Multivariable regression modeling was used to estimate relative risk of patient, surgical, and implant factors for any IOPFF and for all anatomic subtypes of IOPFF. Clinically important interactions were assessed using multivariable regression.ResultsPatient factors significantly increasing the risk of fracture were female gender, American Society of Anesthesiologists grade 3 to 5, and preoperative diagnosis including avascular necrosis of the hip, previous trauma, inflammatory disease, pediatric disease, and previous infection. Overall risk of IOPFF associated with age was greatest in patients below 50 years and above 80 years. Risk of any fracture reduced with computer-guided surgery and in non–National Health Service hospitals. Nonposterior approaches increased the risk of shaft and trochanteric fracture only. Cementless implants significantly increased the risk of only calcar cracks and shaft fractures and not trochanteric fractures.ConclusionFracture risk increases in patients younger than 50 and older than 80 years, females, American Society of Anesthesiologists grade 3 to 5, and indications other than primary osteoarthritis. Large cumulative reduction in IOPFF risk may occur with use of cemented implants, posterior approach, and computer-guided surgery.Level of EvidenceLevel 3b (cohort study).     

Patient-Specific Instrumentation Does Not Affect Rotational Alignment of the Femoral Component and Perioperative Blood Loss in Total Knee Arthroplasty: A Prospective,Randomized, Controlled Trial

BackgroundProposed aims of patient-specific instrumentation (PSI) for total knee arthroplasty (TKA) are to improve accuracy of component alignment, while reducing blood loss and surgical time. The primary goal of this prospective, randomized, controlled, clinical trial is to verify whether PSI improves the rotational alignment of the femoral component in comparison to conventionally implanted TKA.MethodsOne-hundred thirty-three consecutive patients were assessed for eligibility. Block randomization was performed to allocated patients in the treatment (PSI) or control group. During hospital stay, surgical times were recorded, and total blood volume loss and estimated red blood cell were calculated. Two months after surgery, a computed tomography of the knee was obtained to measure femoral component rotation to the transepicondylar axis and tibial component slope.ResultsSixty-nine patients were enrolled. PSI did neither result in a significant improvement in femoral component rotation nor result in a reduction of outliers, as compared with conventional instrumentation.No significant improvement in terms of tibial slope, blood loss, total surgical time, and ischemia time could be identified. The number of tibial recuts required in the PSI group was significantly higher than in the control group (P = .0003).ConclusionPSI does not improve the accuracy of femoral component rotation in TKA in comparison to conventional instrumentation. Moreover, PSI did not appear to influence any of the other variables investigated as secondary goals by this study. The results of this study do not support its routine use during standard TKA.Level of EvidenceLevel I, randomized, controlled trial.     

Incidence,Classification, and Risk Factors for Intraoperative Periprosthetic Femoral Fractures in Patients Undergoing Total Hip Arthroplasty With a Single Stem: A Retrospective Study

BackgroundThe collum femoris preserving (CFP) stem was a specially designed femoral neck preserving component. The incidence, classification, and risk factors for intraoperative periprosthetic femoral fractures with this special stem remain unclear.MethodsThis was a retrospective study. We analyzed the clinical and radiological data of all patients who underwent primary hip arthroplasty with a CFP stem in our hospital between January 2006 and November 2018. Demographic characteristics and radiological features were obtained from the medical records and the Picture Archiving and Communication System, respectively. The incidence, Vancouver classification, and risk factors for intraoperative periprosthetic femoral fractures were identified.ResultsA total of 1633 hips were included. The incidence rate of periprosthetic femoral fractures in patients undergoing total hip arthroplasty with a CFP stem was 3.2%. According to the Vancouver classification, there were 24 patients (45.3%) with Vancouver type A fractures, 27 patients (50.9%) with Vancouver type B fractures, and 2 patients (3.8%) with Vancouver type C fractures. Five independent risk (protective) factors were found, including surgical history (odds ratio [OR] = 3.275, 95% confidence interval [CI] = 1.192-8.997), neck-shaft angle (OR = 1.104, 95% CI = 1.058-1.152), neck length preserved (OR = 0.913, 95% CI = 0.850-0.980), canal flare index (OR = 0.636, 95% CI = 0.413-0.980), and bone mineral density (OR = 0.083, 95% CI = 0.016-0.417).ConclusionThe detailed characteristics of intraoperative periprosthetic femoral fractures in patients who received a CFP stem were identified in this study. Cracks of the femoral neck and fractures on the front side of the proximal femur were more common in patients with CFP stems. As a kind of a femoral neck preserving stem, the anatomical features (eg, neck-shaft angle, preserving length) of the remaining femoral neck might influence the incidence and characteristics of intraoperative periprosthetic femoral fractures in patients with CFP stems.     

Preoperative Radiological Parameters Predicting the Need for Lateral Retinacular Release in Total Knee Arthroplasty

BackgroundProper patellar tracking is essential for well-functioning total knee arthroplasty (TKA). Besides implanting components in the correct position and rotation, balancing parapatellar soft tissues is also important in aiding normal patellar tracking. Patellar maltracking during TKA can be improved by lateral retinacular release (LRR).MethodsWe studied the incidence of LRR in consecutive primary TKA with nonresurfaced patella and posterior-stabilized implant design. We analyzed data from 250 consecutive primary TKAs (212 patients) from January 2016 to May 2016. We evaluated the preoperative radiological parameters like patellar tilt, patellar shift, patellar morphology, Insall-Salvati ratio, femoro-tibial angle, distal femoral valgus angle, and proximal tibia varus angle which predict the need for LRR during TKA. We used multivariate regression analysis to find the association of individual radiological parameters and the LRR.ResultsThe need for LRR is significantly associated with preoperative radiological parameters like patellar shift and patellar tilt (P < .001). Compared to the nonreleased group, the adjusted odds of LRR were greater for morphological parameters like Wiberg type 3 patella (odds ratio [OR] 17.45, 95% confidence interval [CI] 7.21-42.20), lateral facet thinning (OR 4.38, 95% CI 2.37-8.07), lateral patellofemoral arthritis (OR 14.36, 95% CI 6.82-30.23), and coronal valgus deformity (OR 4.95, 95% CI 1.60-10.68).ConclusionPreoperative assessment of these radiological parameters in the axial view implies a high chance of tight lateral retinacular structures. This helps in identifying patients who have a higher likelihood for patellar maltracking during TKA. Appropriate LRR helps to provide better patellar tracking post TKA.     

Asynchronous Bilateral Total Knee Arthroplasty: Predictors of the Functional Outcome and Patient Satisfaction for the Second Knee Replacement

BackgroundThe primary aim of this study is to identify independent preoperative predictors of outcome and patient satisfaction for the second total knee arthroplasty (TKA).MethodsA retrospective cohort of 454 patients undergoing an asynchronous (6 weeks or more apart) bilateral primary TKA were identified from an arthroplasty database. Patient demographics, comorbidities, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Short Form-12 scores were collected preoperatively and 1 year postoperatively. Overall patient satisfaction was assessed at 1 year.ResultsThe 1 year WOMAC pain score (P = .01), and improvement in WOMAC pain (P < .001) and functional (P = .002) scores were significantly lower for the second TKA. Worse preoperative WOMAC pain, function, and stiffness scores were demonstrated to be independent predictors of improvement in the WOMAC pain, function, and stiffness scores, respectively, for both the first and second TKA. The overall rate of satisfaction with the first TKA was 94.0% and 94.7% for the second TKA (P = .67). The rate of satisfaction for the second TKA was 77.8% for patients that were dissatisfied with their first TKA, which was an independent predictor of dissatisfaction (P = .02).ConclusionImprovement in pain and function is less with the second TKA, but the satisfaction rate remains similar. There are common independent predictors for change in the WOMAC score for the first and second TKA; however, the predictors of satisfaction were different with no common factors. Patients that were dissatisfied with their first TKA were more likely to be dissatisfied with their second TKA.Level of Evidence IIPrognostic retrospective cohort study.     

Systematic Review and Meta-Analysis of Intrawound Vancomycin in Total Hip and Total Knee Arthroplasty: A Call for a Prospective Randomized Trial

BackgroundTopical intrawound vancomycin has been used extensively in spine surgery to decrease surgical site infections. However, the efficacy of intrawound vancomycin in total hip (THA) and total knee arthroplasty (TKA) to prevent periprosthetic joint infection (PJI) has not been established.MethodsThe PubMed and MEDLINE databases were searched to identify studies utilizing intrawound vancomycin in primary and revision THA and TKA. Data for postoperative infection were pooled using random effect models with results reported as odds ratios (ORs) and 95% confidence intervals. Studies were weighted by the inverse variance of their effect estimates.ResultsOf the 91 studies identified, 6 low-quality retrospective studies (level III) were pooled for further analysis. A total of 3298 patients were assessed, 1801 of which were treated with intrawound vancomycin. Overall, patients who received vancomycin had a decreased rate of PJI (OR 0.2530, P < .0001). When analyzed separately, TKA patients and THA patients who received intrawound vancomycin had lower rates of PJI (OR 0.3467, P = .0005 and OR 0.3672, P = .0072, respectively). Pooled primary TKA and THA patients receiving vancomycin saw the rate of PJI decrease (OR 0.4435, P = .0046). Pooled revision TKA and THA patients saw a similar decrease in infection rates (OR 0.2818, P = .0013). No apparent publication bias was observed; however, the results from this analysis are limited by the low quality of evidence and inherent potential for bias.ConclusionIntrawound vancomycin may reduce the risk of PJI in primary and revision TKA and THA. However, only low-quality evidence exists, highlighting the need for randomized controlled trials before broad adoption of this practice can be recommended given the potential implications of widespread use of vancomycin in hip and knee arthroplasty.     

Clinical Effectiveness of Aspirin as Multimodal Thromboprophylaxis in Primary Total Hip and Knee Arthroplasty: A Review of 6078 Cases

BackgroundVenous thromboembolism is a serious complication after total hip and knee arthroplasty. There is still no consensus regarding the best mode of thromboprophylaxis after lower limb arthroplasty. The aim of this study was to ascertain the efficacy, safety profile, and rate of adverse thromboembolic events of aspirin as extended out-of-hospital pharmacological anticoagulation for elective primary total hip and knee arthroplasty patients and whether these rates were comparable with published data for low-molecular-weight heparin (LMWH).MethodsData were extracted from a prospective hospital-acquired thromboembolism database. The period of study was from January 1, 2013 to December 31, 2016, and a total of 6078 patients were treated with aspirin as extended thromboprophylaxis after primary total hip and knee arthroplasty.ResultsThe primary outcome measure of deep vein thrombosis and pulmonary embolism within 90 days postoperatively was 1.11%. The secondary outcome rates of wound infection, bleeding complications, readmission rate, and mortality were comparable to published results after LMWH use.ConclusionThe results of this study clearly show that aspirin, as part of a multimodal thromboprophylactic regime, is an effective and safe regime in preventing venous thromboembolism with respect to risk of deep vein thrombosis or pulmonary embolism when compared to LMWH. It is a cheaper alternative to LMWH and has associated potential cost savings.     

Efficacy of Single-Shot Adductor Canal Block Combined With Posterior Capsular Infiltration on Postoperative Pain and Functional Outcome After Total Knee Arthroplasty: A Prospective,Double-Blind,Randomized Controlled Study

BackgroundAdductor canal block (ACB) may preserve muscle strength and promote faster recovery than other methods of analgesia following total knee arthroplasty (TKA). However, there are contradictory reports on the efficacy of ACB. Here, we evaluated the efficacy of single-shot ACB combined with posterior capsular infiltration (PCI) vs multimodal periarticular infiltration analgesia in treating postoperative pain.MethodsThis study involved patients undergoing unilateral primary TKA at our institution from January 2018 to January 2019. Patients were randomized into 2 groups, one of which was treated with ACB combined with PCI, and the other with periarticular infiltration analgesia. Primary outcomes included postoperative pain as assessed by the visual analog scale (VAS) and consumption of morphine hydrochloride. The secondary outcome was functional recovery, as assessed by range of knee motion, quadriceps strength, and daily ambulation distance. Tertiary outcomes included the duration of hospital stay and postoperative adverse effects.ResultsPatients treated with ACB and PCI had lower resting VAS scores at 8 and 24 hours after surgery, and lower VAS scores during motion within 48 hours after surgery. Patients treated with ACB and PCI also consumed less morphine. There was no difference in functional recovery, duration of hospitalization, or incidence of adverse events.ConclusionThe ACB combined with PCI can reduce postoperative pain sooner after TKA without affecting postoperative functional recovery and increasing complications.